Or it could just be that the cable isn't properly in place.. Happened to me, as I had moved the case around a lot, and not fastened the screws as hard as they should... Made my blue desktop turn quite green...
Try reseating your video card, I cannot see any pins getting bent unless you have recently removed the cable. Tap the side of the monitor and see if it changes, move cable up and down at both ends to check for breaks.